The present invention relates to a method and apparatus for making plastic articles, especially wine corks, from plastic resin in a continuous and efficient operation.
Articles such as wine corks as well as others are made using a plastic resin which contains a blowing agent such that after injection of the resin into a mold cavity gas bubbles are formed in the plastic resin. The plastic resin expands in volume as the mold cavity volume is allowed to expand.
Plastic wine corks are particularly useful as they represent an alternative to cork for sealing wine bottles. These and other articles may be prepared by the process described above which is termed "foam molding". This process and apparatus requires that the mold cavity can expand to allow gas bubbles to form in the resin as it cools.
Unfortunately, however, this procedure takes a substantial amount of time as cooling a relatively thick part, particularly a relatively thick part that contains gas bubbles therein, is inherently slow especially due to the very poor thermal transmission properties of the gas filled plastic.